Gas Penetration Research Articles

Chemical Durability Enhancement of Gas Barrier Cellulose Nanocrystal Electrolyte Membranes

Polymer electrolyte fuel cells (PEFCs) system for fuel cell vehicle (FCV) application is one of promising technologies to reduce carbon dioxide emission from transportation sector and mitigate the global warming issue. However, durability of the PEFC system is not enough for commercial requirement, especially heavy-duty vehicles. With regards to polymer electrolyte membranes (PEMs) in the PEFCs system, chemical degradation is the important issue of PEM durability and occurs because of radical attacks during fuel cell operation. One of the routes of radical formation is related to oxygen penetration from cathode to anode through PEMs (Fig. 1, a)[1]. Based on this mechanism, suppressing gas penetration is one of the solutions to alleviate radical attacks to PEMs. To realize this concept, we developed a high gas barrier sandwiched PEM by introducing a cellulose nanocrystals (CNC) interlayer (Fig.1, b, c). CNCs are an abundant biomaterial and have high gas barrier property. To use the biomaterial with high gas barrier, we confirmed the fuel cell performance and chemical durability of the gas barrier PEM.A gas barrier CNC interlayer was sandwiched between two Nafion211 outer layers (Fig.1, c), and the total thickness was about 55µm. Fuel cell performance of the CNC gas barrier PEM was evaluated under 80°C and 95% RH. Then, open-circuit voltage (OCV) holding test, accelerated stress test for PEMs, was performed to evaluate the chemical durability of PEMs under 90°C and 30% RH, and the performance of PEMs were also measured after every 72 hours cycle during OCV holding test by following NEDO protocol.CNC gas barrier PEM could exhibit about 4 times higher gas barrier properties than Nafion211 doble layer (N211DL, 50µm) under 80˚C and dry condition. And the CNC gas barrier PEM could show about 1.6 times longer durability than N211DL in the OCV holding test (Fig. 1, d), indicating that good gas barrier CNC interlayer could suppress radical formation. Therefore, we proved our research concept is available for cellulose nanocrystals, promising for durable PEMs and future PEFCs applications.References Gautama, et. al, J. Membrane Science, 2022, 658, 15, 120734. Figure 1

Numerical simulation of gas penetration and powder compression during high-pressure dynamic load in silo

Numerical simulation of gas penetration and powder compression during high-pressure dynamic load in silo

Engineering Interfacial Molecular Interactions on Ag Hollow Fibre Gas Diffusion Electrodes for High Efficiency in CO2 Conversion to CO.

The electrochemical CO2 reduction reaction (CO2RR) occurs at the nanoscale interface of the electrode-electrolyte. Therefore, tailoring the interfacial properties in the interface microenvironment provides a powerful strategy to optimise the activity and selectivity of electrocatalysts towards the desired products. Here, the microenvironment at the electrode-electrolyte interface of the flow-through Ag-based hollow fibre gas diffusion electrode (Ag HFGDE) is modulated by introducing surfactant cetyltrimethylammonium bromide (CTAB) as the electrolyte additive. The porous hollow fibre configuration and gas penetration mode facilitate the CO2 mass transfer and the formation of the triple-phase interface. Through the ordered arrangement of hydrophobic long-alkyl chains, CTAB molecules at the electrode/electrolyte interface promoted CO2 penetration to active sites and repelled water to reduce the activity of competitive hydrogen evolution reaction (HER). By applying CTAB-containing catholyte, Ag HFGDE achieved a high CO Faradaic efficiency (FE) of over 95 % in a wide potential range and double the partial current density of CO. The enhancement of CO selectivity and suppression of hydrogen was attributed to the improvement of charge transfer and the CO2/H2O ratio enhancement. These findings highlight the importance of adjusting the local microenvironment to enhance the reaction kinetics and product selectivity in the electrochemical CO2 reduction reaction CO2RR.

Modeling and Experimental Validation of Cell Morphology in Microcellular-Foamed Polycaprolactone.

This study investigates the modeling and experimental validation of cell morphology in microcellular-foamed polycaprolactone (PCL) using supercritical carbon dioxide (scCO2) as the blowing agent. The microcellular foaming process (MCP) was conducted using a solid-state batch foaming process, where PCL was saturated with scCO2 at 6 to 9 MPa and 313 K, followed by depressurization at a rate of -0.3 and -1 MPa/s. This study utilized the Sanchez-Lacombe equation of state and the Peng-Robinson-Stryjek-Vera equation of state to model the solubility and density of the PCL-CO2 mixture. Classical nucleation theory was modified and combined with numerical analysis to predict cell density, incorporating factors such as gas absorption kinetics, the role of scCO2 in promoting nucleation, and the impact of depressurization rate and saturation pressure on cell growth. The validity of the model was confirmed by comparing the theoretical predictions with experimental and reference data, with the cell density determined through field-emission scanning electron microscopy analysis of foamed PCL samples. This study proposes a method for predicting cell density that can be applied to various polymers, with the potential for wide-ranging applications in biomaterials and industrial settings. This research also introduces a Python-based numerical analysis tool that allows for easy calculation of solubility and cell density based on the material properties of polymers and penetrant gases, offering a practical solution for optimizing MCP conditions in different contexts.

Boosting pH-universal electrosynthesis of hydrogen peroxide by regulating three-phase interface of carbon gas penetration electrode

Electrochemical oxygen reduction is a sustainable method for onsite H2O2 production. However, pH-universal H2O2 electrosynthesis still suffered from low kinetics and efficiency. Here carbon nanotube hollow fiber (CNT-HF) with porous fiber wall is designed to enhance H2O2 electrosynthesis via tailoring the three-phase interface. The CNT-HF gas penetration electrode with enhanced local electric field is favorable for boosting oxygen mass transfer and regulating catalyst-electrolyte interfacial protons, resulting in significantly enhanced H2O2 production performance in comparison with CNT planar gas diffusion electrode under pH-universal media. Its H2O2 production efficiency is 98.1% at pH 13. Meanwhile, H2O2 production efficiency of 96.1% and high H2O2 concentration of 46.4 g L-1 are achieved at pH 1 with 20 mM K+. Experimental and simulation results reveal the boosted H2O2 electrosynthesis on CNT-HF is mainly contributed from its significantly reduced diffusion layer thickness, enhanced local electric field and interfacial proton regulation by K+ enriched at electrode surface.

Investigating the Consequence s of Energy Transitions in Protracted Displacement Settings: Solid Fuel Dependency and IDPs’ Readiness

Abstract Looking beyond cooking energy provision in humanitarian response, interventions define the course of the internally displaced people’s (IDPs) livelihood. Energy transition in displacement settings often puts the bar high as the outputs are aimed to provide full use of low emission, healthy, clean cooking energy sources. By gathering data from protracted temporary settlements inhabited since 2012 by those affected by the Mount Sinabung eruption in Karo Regency, Indonesia, the purpose of this study is to look into how Internally Displaced Persons (IDPs) are switching to greener energy sources for cooking. A framework for determining energy choice at the household size was employed to depict the overview of energy use in cooking, taking into account the effects of the transition. The case of Sinabung displacement offered a perspective of the prolonged IDPs on humanitarian energy interventions and the national ecosystem toward clean energy behaviour. Even though Liquid Petroleum Gas (LPG) penetration is subsidized, a protracted displacement situation in Sinabung still reveals solid fuel dependencies. The LPG subsidy program, which was poorly planned, and the lack of readiness of IDPs to purchase and use new alternative cooking energy were the biggest obstacles to the overall transition process and caused the fuel stacking phenomenon to persist.

Experimental study on CO2 sequestration performance of alkali activated fly ash and ground granulated blast furnace slag based foam concrete

In an effort to reduce the emission level of carbon dioxide (CO2) from metallurgical, thermal, cement burning and other enterprises, an innovative solution is proposed in this study, which aims to sequester CO2 with alkali activated fly ash (FA) and ground granulated blast furnace slag (GGBFS) based foam concrete. The fluidity of alkali activated foam concrete (AAFC) fresh paste, dry density and compressive strength after hardening, micro-pore structure, carbonation products and CO2 sequestration capacity were comprehensively explored. The experimental findings indicated that the fluidity of AAFC slurry was almost unaffected by the content of foaming agent hydrogen peroxide (H2O2). When the H2O2 content ranges between 1 % and 3 %, the dry density of uncarbonated AAFC ranges approximately 752.3–365.2 kg/m3, and the compressive strength of carbonated AAFC ranges about 1.01–0.21 MPa. Accelerated carbonation increased the dry density of uncarbonated AAFC samples. The porous structure of AAFC facilitated CO2 gas penetration into the matrix, leading to rapid carbonation. When the H2O2 content was 1 %, the compressive strength of fully carbonated AAFC was lower than that of non-carbonated AAFC; however, when the H2O2 content exceeded 1.5 %, the trend in compressive strength reversed. The carbonation kinetics of AAFC demonstrated a linear relationship with the square root of carbonation time, and the carbonation coefficient increases proportionally with H2O2 content. The porosity of AAFC increased from 61.05 % to 71.51 % as the H2O2 content increased from 1 % to 2.5 %. The main pore size distribution range of AAFC was 30–400 µm and 5–50 nm. Accelerated carbonation minimally impacted the total porosity of AAFC but transformed certain large pores into capillary pores. Accelerated carbonation would generate calcite, aragonite, vaterite and additional amorphous phases. The maximum carbon sequestration capacity of AAFC, as determined in this study, reached 26.41 kg/m3, indicating significant potential for CO2 sequestration.

A Review of Early Gas Intrusion Detection based on Multiphase Flow Model

High content gas reservoirs in deep reservoirs have complex pressure systems, and gas penetration occurs frequently during drilling, trip or other drilling operations. Due to the compressibility of gas and its easy solubility in drilling fluid, gas penetration in ultra-deep Wells is often sudden and hidden. In the early stage, it is difficult to find and fully alleviate gas invasion, which is very easy to induce blowout accidents. Accurate prediction and control of gas invasion is of great significance to prevent blowout accidents. In the past 20 years, the research of early gas invasion detection has made great progress. This paper aims to provide the latest progress of early gas intrusion detection based on transient multiphase flow, and make a comprehensive review of early gas intrusion detection. The specific contents include: 1. 2. The development of numerical simulation of early gas invasion detection is summarized. 3. The influencing factors of early gas intrusion detection modeling are analyzed. 4. The application of drift flux model in each flow pattern is introduced. 5. The importance of gas solubility and heat transfer in numerical simulation of gas penetration detection is analyzed. 6. The current development of early gas invasion detection was summarized and the future prospect was made.

Numerical investigation on direct water injection characteristics under different injection and ambient conditions within oxygen/argon atmosphere

Improving efficiency and reducing emissions are essential to achieve carbon neutrality in transportation sector. The hydrogen-fueled argon power cycle (H2-APC) is a novel power system with high efficiency and zero emission by utilizing argon-oxygen mixture as working fluids. However, knock suppression is a problem within H2-APC engines. Direct water injection (DWI) is an effective method to inhibit detonation. Spray morphology greatly influences the effectiveness of DWI, the investigation of spray characteristics in oxygen/argon atmosphere is critical. This paper established a computational model based on experimental data to investigate DWI characteristics under different injection and ambient conditions within oxygen/argon atmosphere. The results reveal increased jet temperature leads to stronger superheated jet spray collapse, while Sauter mean diameter (SMD) decreases and atomization improves. Increasing jet pressure effectively reduces spray SMD and improves atomization effect and evaporation rate. Higher ambient temperature reduces ambient gas density, spray SMD and penetration are decreased and increased, respectively. Moreover, spray evaporation rate and evaporated mass are dropped with higher ambient pressure for both superheated and subcooled sprays. As ambient density rises, the capacity for jet perturbation and fragmentation is enhanced, and spray SMD decreases. The research results can provide an effective guide for the DWI strategy of H2-APC engines.

Pore evolution and reaction mechanism of coal under the combination of chemical activation and autothermal oxidation

Aiming at the limitation problems such as limited scope, high cost and energy consumption of coal bed penetration enhancement technology by traditional physical and chemical methods, a coal seam methane penetration enhancement method based on the combined action of chemical activation and auto thermal oxidation is proposed from the idea of utilizing the in-situ energy of the coal body. In this paper, N2 and CO2 adsorption, XPS and FTIR methods are used to study the pore structure evolution law and the change characteristics of the reactive structure of coal matrix under the effect of chemically activated autothermal oxidation. The synergistic microporous pore volume of chemical activation and auto thermal oxidation was 48.91 cm3/g−1 × 10-3, which was 28.96 % and 22.7 % higher than chemical activation and auto thermal oxidation respectively; The microporous specific surface area was 162.7 m2/g, which was 38 % and 26.6 % higher than chemical activation and auto thermal oxidation respectively. Activated coals expand and merge holes to a deeper degree after oxidative warming, and the complexity of the pore structure in the coal decreases; Highly reactive radicals in coal pores substantially promote the oxidation of coal structure, enhance the aromatic polymerization reaction of activated coal, and improve the maturity and aromaticity of activated coal, and the oxygen-containing functional groups in activated coal are negatively correlated with the oxidation temperature. The results of this study reveal the potential of the auto thermal oxidation-driven penetration enhancement method under chemical activation for coal seam gas penetration enhancement and extraction.

Numerical and Experimental Analyses of the Effect of Water Injection on Combustion of Mg-Based Hydroreactive Fuels

The energy release process of the Mg-based hydroreactive fuels directly affects the performance of water ramjet engines, and the burning rate is one of the key parameters of the Mg-based hydroreactive fuels. However, there is not enough in-depth understanding of the combustion process of Mg-based hydroreactive fuels within the chamber of water ramjet engines, and there is a lack of effective means of prediction of the burning rate. Therefore, this paper aims to examine the flame structure of Mg-based hydroreactive fuels with a high metal content and analyze the impact of the water injection velocity and droplet diameter on the combustion property. A combustion experiment system was designed to replicate the combustion of Mg-based hydroreactive fuels within water ramjet engines, and the average linear burning rate was calculated through the target line method. On the basis of the experiment, a combustion–flow coupling solution model of Mg-based hydroreactive fuels was formulated, including the reaction mechanism between Mg/H2O and the decomposition products from an oxidizer and binder. The model was validated through experimental results with Mg-based hydroreactive fuels at various pressures and water injection velocities. The mean absolute percentage error (MAPE) in the experimental results was less than 5%, proving the accuracy and validity of the model. The resulting model was employed for simulating the combustion of Mg-based hydroreactive fuels under different water injection parameters. The addition of water injection resulted in the creation of a new high-temperature region, namely the Mg/H2O non-premixed combustion region in addition to improving the radial diffusion of the flame. With the increasing water injection velocity, the characteristic distance of Mg/H2O non-premixed combustion region is decreased, which enhances the heat transfer to burning surface and accelerates the fuel combustion. The impact of droplet parameters was investigated, revealing that larger droplets enhance the penetration of the fuel-rich gas, which is similar to the effect of injection velocity. However, when the droplet size becomes too large, the aqueous droplets do not fully evaporate, resulting in a slight decrease in the burning rate. These findings enhance the understanding of the mechanisms behind the burning rate variation in Mg-based hydroreactive fuels and offer theoretical guidance for the optimal selection of the engine operating parameters.

Computational Fluid Dynamics Modeling of Multiphase Flows in a Side-Blown Furnace: Effects of Air Injection and Nozzle Submerged Depth

The side-blown smelting process is becoming popular in the modern metallurgical industry due to its large potential for dealing with complex materials. To further enhance its efficiency, it is essential to comprehensively understand the complex gas–liquid flow behavior in the smelting bath. In this study, the volume-of-fluid method is employed to establish computational fluid dynamics modeling on a 1:5 scaled model of a side-blown furnace. The simulation was validated against the experimental results. Notably, the influences of the nozzle’s submerged depth, injection velocity, and angle were systematically investigated. The results show that increasing the injection velocity from 29.44 to 58.88 m/s resulted in 52.97%, 116.67%, 500.00%, and 5.88% increases in the interface area, liquid velocity, liquid turbulent kinetic energy, and gas penetration depth, respectively. The maximum gas–liquid interface area, gas penetration depth, velocity, and turbulence of the liquid were found at an injection angle of 30°. Furthermore, increasing the submerged depth increased the interface area and the velocity of the liquid but decreased the turbulent kinetic energy of the liquid. Overall, increasing the injection velocity is considered a more effective measure to strengthen the smelting intensity.

The Effects of Preheating the Shielding Gas Used in Gas Tungsten Arc Welding

The shielding gas used in welding processes has properties that can affect the operating characteristics of electric welding arcs. Characteristics such as welding voltage, heat input, and thermal profile, which in turn affect weld geometry, are strongly influenced by the properties of the gas used. Thus, this work aimed to evaluate how preheating the shielding gas influences the gas tungsten arc welding (GTAW) process. For this, a heating system was developed that allowed the variation and control of the gas exit temperature during the tests. A methodology for studying the electric arc was proposed, evaluating the voltagecurrent, profile, and luminosity values. Autogenous welds were performed on carbon steel plates with different gas temperatures, and penetration and width were observed. The results showed that the use of gas preheating influenced the characteristics of the arc and, consequently, weld geometry.

Carbon capturing composite membranes comprising Cu‐MOF and PIM‐1

AbstractCarbon capture from different CO2‐enriched sources demands the establishment of cleaner innovations to make strides in improving the existing worldwide environment. Nanoparticles of inorganic copper‐based metal–organic framework (Cu‐MOF) have been impregnated in varying loadings into an intrinsically microporous polymer (PIM‐1) to concoct mixed‐matrix membranes (MMMs) for carbon capture applications. The impacts of Cu‐MOF doping and temperatures of feed gas streams on morphology and carbon detainment capability of manufactured membranes were investigated. The carbon seizing capacity of different membranes was assessed by estimating permeabilities, selectivities, dissemination and dissolvability coefficients, facilitation proportions, and activation energies. Compared with the unfilled PIM‐1 membrane, impregnation of 30% Cu‐MOF into polymer significantly enhanced CO2 penetrability from 3740 to 6360 Barrer together with CO2/N2 and CO2/CH4 selectivity advancements from 27 to 34 and from 16 to 18, respectively. Performing gas penetration tests at elevated temperatures raised the CO2 penetrability of the membrane. The carbon seizing capability of MMMs lying over Robeson's bound signifies their potential in various cleansing operations.

Investigating Hydrocarbon Gases Permeability Through Hollow Fiber Hybrid Carbon Membrane

Hydrocarbon separation from natural gases is a critical procedure in the chemical and petrochemical industries. This study used hollow fiber carbon membranes (HFCMs) made from a commercially available co-polyimide, P84, with zeolite-carbon composite (ZCC) as a filler to separate light hydrocarbons like CH4/C3H8 and CH4/C2H6. The Arrhenius technique was used to evaluate the effects of temperature fluctuations (298, 323, and 373 K) on the membrane. X-ray diffraction exhibited a characteristic graphite peak at 2θ ~ 44°, indicating the creation of an effective carbon membrane. SEM investigation revealed the compactness of both pristine and hybrid carbon membrane structures. The operating temperature has a significant influence on the gas penetration through the membrane when evaluating gas permeation. The hybrid carbon membrane has the highest permeability for CH4, C2H6, and C3H8 at 373 K. (81.86, 61.82, and 58.28 Barrer, respectively). The carbon membrane also showed greatest selectivity for CH4/C3H8 and CH4/C2H6 at 323 K (2.24 and 2.04, respectively). Adsorption and surface diffusion were the membrane's transport mechanisms. By adding filler to the membrane, the gas permeability was temperature dependent.

A Combined Experimental and Turbulence-Resolved Modeling Approach for Aeroengine Turbine Rim Seals

Abstract Ingress is the penetration of hot mainstream gas into the rotor–stator wheel-space formed between adjacent disks; a rim seal is installed at the periphery of the wheel-space. Purge flow is bled from the compressor and re-introduced in the turbine to reduce, or in the limit prevent, ingress. This study presents a unique, concomitant experimental and turbulence-resolved numerical investigation of ingress in an aeroengine rim seal, with leakage flow. Experimental modeling is conducted in the University of Bath's 1-stage turbine test facility. Measurements of gas concentration, pressure and swirl were used to assess the performance of the rim seal. A parallel study using improved delayed detached eddy simulations (IDDES) was used to generate time-averaged and time-resolved flow-fields, enabling direct comparison with experimental data. The modeled geometry included realistic features typical of aeroengine architectures, including a contoured stator undershroud and an omega-seal cover plate. Such features were shown to locally distort the flow field, highlighting the limitation when modeling simplified geometry. The circumferential distribution of sealing effectiveness was nonaxisymmetric and synchronized in accordance with the local radial velocity field. Utilization of a detached eddy simulation (DES) turbulent kinetic energy (TKE) dissipation multiplier demonstrated regions where increased turbulence resolution was required to resolve the appropriate scale of turbulent eddies. IDDES computations were found to accurately capture the radial distributions of pressure, swirl and effectiveness, both in the absence and presence of a superposed leakage flow, provided that the mesh was sufficiently refined so as to resolve ≥50% of the energy cascade. The IDDES approach exhibited significantly superior agreement with experiments when compared to previous studies that employed the unsteady Reynolds-averaged Navier–Stokes (URANS) methodology.

Instabilities of a circular moderately dense particle cloud impacted by an incident shock

Shock-driven gas-particle flows exist in a wide variety of physical systems, covering the range from dilute to dense regime. There are a lot of fundamental questions remaining to be answered, like the evolutions of flow instability, two-phase interactions, and inter-particle collision effects. In this work, the Eulerian-Lagrangian approach with gas-particle four-way coupling is applied to model two-dimensional shock-driven gas-particle flow under the moderately dense regime. For the gas flow, the formation mechanism of primary and secondary vortexes is discussed. The primary vortex is caused by the roll-up of slip line, while the secondary vortexes are induced by the velocity and density difference between the penetrating flow of particle-laden zone and the outside mainstream. Parametric studies of different Mach numbers, particle diameters and initial volume fractions have been performed to investigate the effects on shock behaviours and slip line instabilities. For the particle phase, a high-volume-fraction compression region forms at the upstream cloud zone, which blocks the penetrating gas, and results in the formation of slip line. The cloud tail is mainly composed of the upstream edge particles. The inter-particle collisions have impact on the particle distributions, and greatly affect the slip line stability at the upstream cloud edge. This work provides valuable insights into the instability mechanism of compressible gas-solid flow and the particle dispersion behaviours. However, it is important to note that our analysis is based on a two-dimensional configuration. In a real three-dimensional context, the generation of vortices is likely to differ, and may affect the particle dynamics to a certain degree.

Experimental study on the Klinkenberg effect for gas permeability in carboniferous shales, Eastern Qaidam Basin, China

It is crucial to understand the conditions and influencing mechanisms of shale gas slip effect for predicting the productivity of shale gas reservoirs. This study focuses on the Carboniferous Hurleg Formation shales in the eastern Qaidam Basin and conducts gas permeability tests using different gases (He/N2), as well as geochemical and pore-structure tests. The slip behavior of different gases in micro- and nanopores as well as the anisotropy of gas permeability were analyzed and discussed. The results show that helium permeability is 1.81–3.56 times higher than nitrogen permeability, with a greater difference at lower pore pressures. These permeability differences are attributed to variations in gas molecule size and slip effects. Specifically, the slip effect of helium gas has a greater contribution to permeability at lower pore pressures, with a helium slip factor averaging 2.79 times that of nitrogen. The effective pore size of shale, calculated based on the helium slip factor, is 0.74 to 1.51 times larger than when nitrogen is used, with an average of 1.67 times. Helium molecules have smaller diameters and longer average molecular free paths, resulting in a more pronounced slip effect compared to nitrogen. While helium does not adsorb, nitrogen exhibits some adsorption, causing radial expansion during gas penetration. Furthermore, when testing with different gases, the horizontal permeability (S043∥; S052∥) is higher than the vertical permeability (S043⊥; S052⊥). The anisotropy of permeability is controlled by the pore system formed by the arrangement and combination of minerals. Calcium-rich samples (S052) tend to exhibit higher anisotropy compared to calcite-rich samples (S043). The effective pore size in the vertical sample is larger than that in the parallel sample, and the gas slip effect is significantly greater in the vertical sample. These findings provide valuable data for future studies on shale gas slip effects and productivity prediction.

Experimental and numerical investigations of damage and ballistic limit velocity of CFRP laminates subject to harpoon impact

The harpoon is a space debris capture mechanism with strong adaptability to targets. In this paper, experiments and finite element models are used to study the harpoon impact on carbon fiber laminate. Firstly, a harpoon penetration gas gun experiment was designed to obtain the damage and ballistic limit velocity of carbon fiber laminates. Then finite element modeling and numerical simulation of the impact on the laminate were carried out using the user–defined VUMAT subroutine in ABAQUS, focusing on the ballistic limit velocity change, damage evolution of the laminate and energy absorption of the laminate when the harpoon penetrates the laminate obliquely at a specific angle. The results showed that compared with vertical penetration, the ballistic limit velocity of harpoon increased by 3.2 %, 9.6 % and 24.3 % respectively under 15°, 30° and 45° oblique penetration conditions; and with the increase of harpoon impact angle, the damage of laminates gradually tended to occur on one side of the projection of harpoon on laminates; while in terms of energy absorption, the energy absorption of laminates for the same angle tended to a constant value as the launch velocity increased.

Nano boron nitride laminated poly(ethyl methacrylate)/poly(vinyl alcohol) composite films imprinted with silver nanoparticles as gas barrier and bacteria resistant packaging materials

AbstractHerein, nano boron nitride (BN) laminated poly(ethyl methacrylate) (PEMA)/poly(vinyl alcohol) (PVA) nanocomposite films are fabricated by using a simple in situ polymerization technique with incorporation of silver nanoparticles (Ag NPs). Structural investigations of PEMA/PVA/Ag@BN nanocomposite thin films are carried out by Fourier‐transform infrared spectroscopy, dynamic light scattering, X‐ray diffraction analysis, 1H nuclear magnetic resonance, 13C nuclear magnetic resonance, and mass spectrometry. The change in morphology of PEMA/PVA matrix due to the reinforcement of BN platelets are identified by electron microscopic studies. The unique tortuous paths are achieved by the dispersion of BN platelets by which gas penetration is restricted with enhancing the barrier properties of the material by 6.5 folds at 5 wt% BN content as compared with neat PEMA/PVA. Acid and alkali resistant along with biodegradability behavior of as‐synthesized nanocomposites are studied. From limiting oxygen index (LOI) results, it is found that the prepared materials are fire retardant in nature owing to effective reinforcement of BN layers. Antibacterial activities of PEMA/PVA/Ag@BN nanocomposite are studied by Xanthomonas citri or axonopodis pv. Citri, Escherichia coli, and Xanthomonas oryzae pv. Oryzae because of Ag NPs reinforcement. The substantial improvements in gas barrier, fire retardant, and antibacterial properties enable the materials for packaging application.